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Articles 1051  1063 of 1063
FullText Articles in Physical Sciences and Mathematics
Rotational Excitation Of Polar Molecules By Electrons, Marvin H. Mittleman, Jerry Peacher, Balazs F. Rozsnyai
Rotational Excitation Of Polar Molecules By Electrons, Marvin H. Mittleman, Jerry Peacher, Balazs F. Rozsnyai
Physics Faculty Research & Creative Works
Rotational excitation of polar molecules is calculated in the approximation that the electron transit time is short compared with rotational periods with the result of an E^{1} behavior of the cross section. Diffusion cross sections are calculated for Δl=0,1,2. Significant corrections to the Born approximation are obtained for large dipole moments. The range (in energy) of applicability of the result is discussed in terms of the energy dependence of the corrections, and a novel energy dependence of these corrections is encountered and explained.
Modified Phase Representation And Effects Of Inelasticity In N/D Calculation Of PWave PionPion Scattering, Barbara N. Hale, Arnold Tubis
Modified Phase Representation And Effects Of Inelasticity In N/D Calculation Of PWave PionPion Scattering, Barbara N. Hale, Arnold Tubis
Physics Faculty Research & Creative Works
An N/D formalism based on a modified phase representation is used to study the effects of inelasticity on the ρwave pionpion amplitude. The effects of highenergy inelasticity are introduced in terms of the assumed behavior of the highenergy phase (not phase shift) of the partialwave amplitude. Using a ρexchange input force with the experimental ρ mass and a ρ width of about 100 MeV, and the assumption that the average phase is (1/2)π, for total c.m. energies greater than about 8M_{π}, we find that there is no appreciable reduction in the width of the calculated ...
Critical Assessment Of The PolarizedOrbital Method In Atomic Scattering, Marvin H. Mittleman, Jerry Peacher
Critical Assessment Of The PolarizedOrbital Method In Atomic Scattering, Marvin H. Mittleman, Jerry Peacher
Physics Faculty Research & Creative Works
The method of polarized orbitals used in calculating electronatom scattering amplitudes has two obvious flaws: the wave function is discontinuous, and the method is not variationally based. These are corrected in a somewhat arbitrary manner, and it is found that the results then depend upon a parameter of the theory sufficiently strongly that there are serious doubts about the predictive nature of the theory.
Modified Dispersion Relations And Π Π Scattering, David J. George, Barbara N. Hale, Arnold Tubis
Modified Dispersion Relations And Π Π Scattering, David J. George, Barbara N. Hale, Arnold Tubis
Physics Faculty Research & Creative Works
The ππ Swave scatteringlength predictions of Weinberg have been tested by using dispersion sum rules for the infiniteenergy cross section. Reasonable agreement is obtained with the infiniteenergy cross section (≈15 mb) estimated from the factorization theorem for the Pomeranchon Regge residues. Experimental phaseshift data of Gutay et al., Walker et al., and Baton et al. are used in estimating the dispersion integrals. The analysis seems to rule out an I = 0 Swave scattering length ⪞0.4μ^{1}.
New Superconvergent Dispersion Relations For The Forward Πn CrossingEven Amplitude, David J. George, Barbara N. Hale, Arnold Tubis
New Superconvergent Dispersion Relations For The Forward Πn CrossingEven Amplitude, David J. George, Barbara N. Hale, Arnold Tubis
Physics Faculty Research & Creative Works
A LiuOkubotype dispersion relation is derived for the crossingeven pionnucleon forward elastic scattering amplitude T^{(+)}. Two subtractions are made, one at the physical scattering threshold and the other at a previously determined zero of T^{(+)} on the imaginary axis of the complex ω (pion lab energy) plane. The dispersion relation is well satisfied over the whole allowed range of the LiuOkubo parameter. Moreover, it is nearly saturated by lowenergy scattering for a considerable range of the parameter. It should thus serve as an extremely sensitive test of the lowenergy scattering data when such data become more accurately known.
Associative Detachment: H+Hˉ→₂^{*}+E, Joseph C.Y. Chen, Jerry Peacher
Associative Detachment: H+Hˉ→₂*+E, Joseph C.Y. Chen, Jerry Peacher
Physics Faculty Research & Creative Works
The process of associative detachment in the (H,H^{}) collision system is investigated at energies below 12 eV. In this energy region, the interaction potential between H and H^{} has recently been determined. The energy dependence of the cross section is calculated with explicit allowance for the production of "hot" hydrogen molecules. It is observed that associative detachment provides a possible mechanism for generating an inverted population of the residual molecule such as H_{2}.
Interaction Potential Between The Ground States Of H And Hˉ, Joseph C.Y. Chen, Jerry Peacher
Interaction Potential Between The Ground States Of H And Hˉ, Joseph C.Y. Chen, Jerry Peacher
Physics Faculty Research & Creative Works
An investigation of the interaction potential for H and H^{} in both ungerade and gerade modes is carried out by a semiempirical method in which the recently observed isotope effect in dissociative attachment of electrons to hydrogen molecules is used. The interaction obtained is complex, and the imaginary parts of the interaction account for electron emissions during the course of the interaction. A comparison of the present result with other calculations is presented. The isotope effect in dissociative attachment is also discussed. It is shown that the ratios of the survival probabilities alone do not provide an adequate approximation for ...
Dielectric Properties Of Solid Solutions Of Bifeo₃ With Pb(Ti, Zr)O₃ At High Temperature And High Frequency, Robert Travis Smith, Gary D. Achenbach, Robert Gerson, William Joseph James
Dielectric Properties Of Solid Solutions Of Bifeo₃ With Pb(Ti, Zr)O₃ At High Temperature And High Frequency, Robert Travis Smith, Gary D. Achenbach, Robert Gerson, William Joseph James
Physics Faculty Research & Creative Works
Solid solutions of BiFeO_{3} with PbTiO_{3}, PbTi_{0.5}Zr_{0.5}O_{3}, and PbZrO_{3} were prepared. The crystallographic data on these solutions, which are basically perovskitic, are given. The dielectric constants of the materials were determined at a frequency of 0.53 GHz and at temperatures up to 800°C. Dielectric Curie points were found in solutions containing up to 90 mole % BiFeO_{3}. These results leave little doubt that BiFeO_{3} is ferroelectric or antiferroelectric. The extrapolated Curie point for BiFeO_{3} is above 850°C. BiFeO_{3} appears more likely to be ferroelectric ...
Survival Probability In Dissociative Attachment, Joseph C.Y. Chen, Jerry Peacher
Survival Probability In Dissociative Attachment, Joseph C.Y. Chen, Jerry Peacher
Physics Faculty Research & Creative Works
The survival probability in dissociative attachment is investigated with special attention to the (e, H_{2} ) system. It is shown that the simple expression for the dissociativeattachment cross section, as given by the product of a capture cross section and a survival probability, is equivalent to the s wave approximation for the g → g dissociative attachment. This expression, however, does not constitute an approximation for the g → u dissociative attachment, since the parity of the initial rotational states of H_{2} is always opposite to that of the relative angular momentum states of H and H^{} and the capture cross ...
Rapid Calculation Of Electron Scattering Factors, Jerry Peacher, John G. Wills
Rapid Calculation Of Electron Scattering Factors, Jerry Peacher, John G. Wills
Physics Faculty Research & Creative Works
The phase amplitude method is used to reduce the radial Schrödinger equation to two separate differential equations, one for the phase and one for the amplitude. These functions are both smooth as opposed to the rapidly oscillating solution of the radial Schrödinger equation for electron energies in the kilovolt range. The partialwave phase shifts were obtained rapidly by integrating the differential equations for the phase and amplitude numerically. HartreeFock and ThomasFermiDirac fields were used in the calculation. Results for argon and uranium are given in order to compare with previous results. It was found that the WKBJ approximation to the ...
Ferroelectric Properties Of Pbzro₃Bifeo₃ Solid Solutions, Robert Gerson, PenChu Chou, William Joseph James
Ferroelectric Properties Of Pbzro₃Bifeo₃ Solid Solutions, Robert Gerson, PenChu Chou, William Joseph James
Physics Faculty Research & Creative Works
Solid solutions of BiFeO and PbZrO_{3} were investigated for crystallographic and dielectric properties. A new pseudocubic perovskite phase was found, which has been tentatively indexed as orthorhombic with the same unit cell as PbZrO_{3} but with dielectric properties characteristic of a ferroelectric substance. The Curie point in this series of solid solutions has a minimum of about 155°C at a composition of about (PbZrO_{3})_{0.80} (BiFeO_{3})_{0.20}, which at room temperature lies on the boundary between the orthorhombic antiferroelectric and the pseudocubic ferroelectric phases. This composition has a relative dielectric constant of 800 ...
On The Calculation Of Multicenter TwoElectron Repulsion Integrals Involving Slater Functions, Russell A. Bonham, Jerry Peacher, Henry L. Cox
On The Calculation Of Multicenter TwoElectron Repulsion Integrals Involving Slater Functions, Russell A. Bonham, Jerry Peacher, Henry L. Cox
Physics Faculty Research & Creative Works
Integral transforms are used to evaluate manycenter twoelectron repulsion integrals involving Slater stype functions. The reduction of a general fourcenter integral of this type to a form convenient for computational purposes is presented. The technique described has the important advantage that all lesser manycenter and onecenter integrals can be obtained from the fourcenter case by proper choice of constants. The form of the result is such that simple singleprecision numerical techniques yield rapid and accurate evaluations of manycenter integrals. Several numerical examples are presented.
Theory Of The Effect Of Temperature On The Electron Diffraction Patterns Of Diatomic Molecules, Russell A. Bonham, Jerry Peacher
Theory Of The Effect Of Temperature On The Electron Diffraction Patterns Of Diatomic Molecules, Russell A. Bonham, Jerry Peacher
Physics Faculty Research & Creative Works
The effect of temperature on the electron diffraction pattern of a diatomic molecule is considered from the standpoint of the simple kinematic scattering theory utilizing a quartic vibrational potential. The potential is obtained by an expansion of ħ^{2}J( J+1)/2μr^{2}+D exp[2a(rr_{e})]2D exp[a(rr_{e})] about its minimum value r_{0}. The secondorder wavefunction for the nth vibrational and 7th rotational state of the system has been obtained, and expressions for the electron diffraction quantities r_{g}, l_{e} ^{2}, and M (s) have been computed. General results for the quantity M ...